Effective early intervention depends on reliable identification of risk for communication impairments as soon as possible. Established infant risk factors for communication impairments include poor turn taking, gestures, receptive language, commenting, symbolic play, and speech. Although these risk factors can be detected by 12-18 mos. and reliably predict later language and social development, attempts to detect similar risk factors in children 2-12 mos. have been unsuccessful because of extreme limitations in available assessments that typically include only 4-6 items for these infants' preintentional communication (i.e., reactive or active infant communication behaviors that are not directed toward listeners). There are no available normed assessments that provide comprehensive and dynamic data on infant preintentional communication and reflect evidence-based predictors that discriminate infants at risk for communication impairments before 12 months. When practitioners cannot detect infant behaviors known to be associated with communication risk, they cannot target early intervention to children with the greatest needs and potential for improvement. If we can identify communication risk early enough, we can intervene in the skills that predict later communication impairments and potentially mitigate effects of primary impairments in children and reduce the likelihood of secondary impairments that affect communication and other life skills. The plan for this project is to refine and complete norming for a predictive, comprehensive, modality-independent assessment to detect communication risk in preintentional infants 2-12 months (the Infant Social Communication Behavior Scales, or ISCBS). Phase I research by the present grant team showed that a short probe could reliably elicit preintentional communication behaviors from infant's age 2-12 months that represent 12 predictors of communication risk. These 12 predictors can be reliably and validly scored and grouped into 6 domains that correspond to 6 behavior clusters for the leading dynamic communication assessment for toddlers, the Communication and Symbolic Behavior Scales (CSBS; Wetherby & Prizant, 1993). A clear prediction of communication risk could justify the early involvement of speech-language pathologists for infants as well as for older children who have complex communication needs. We will do final revisions of the ISCBS based on Phase I results and create nationally representative norms by administering the ISCBS to 220 new samples of typically developing infants 2-12 mos., and conducting follow-up assessments with these infants and a previous cohort of 134 infants at 30-36 mos. for a total normative sample of 354 children, to achieve these specific aims: refine the ISCBS, and associated training materials to improve ease of administration and scoring, confirm ISCBS items, scales, domains, and composite that account for domains that discriminate by age and at-risk disability status at three years from ISCBS infant samples, and establish the reliability, validity and age-based norms of the scales, domains, and composite scores for the ISCBS in nationally representative samples of typically developing infants using correlational analyses, including confirmatory factor analysis.